Answer:
As water freezes, a crystalline structure preserved by hydrogen bonding is formed by water molecules. Less dense than liquid water is solid water, or ice. Ice is less dense than water since molecules are pulled farther apart by the direction of hydrogen bonds, which decreases density.
Explanation:
This compound is also known as Barium Carbonate. 1 mole is equal to 1 moles BaCO3, or 197.3359<span> grams.</span>
ANSWER:
4 a) Specific elements have more than one oxidation state, demonstrating variable valency.
For example, the following transition metals demonstrate varied valence states: 
, 
, 
, etc.
Normal metals such as 
also show variable valencies. Certain non-metals are also found to show more than one valence state 
4 b) Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons.
For example, Carbon-14 is a naturally occurring radioactive isotope of carbon, having six protons and eight neutrons in the nucleus. However, C-14 does not last forever and there will come a time when it loses its extra neutrons and becomes Carbon-12.
5 a) 
→ 
5 b) 
→ 
5 c) 
→ 
(already balanced so don't need to change)
5 d) 
→ 
5 e) 
→ 
EXPLANATION (IF NEEDED):
1. Write out how many atoms of each element is on the left (reactant side) and right (product side) of the arrow.
2. Start multiplying each side accordingly to try to get atoms of the elements on both sides equal.
EXAMPLE OF BALANCING:
Answer: Anna stated that ionic compounds have high melting point and low boiling point. The error in the statement is that ionic compound have low boiling point, instead ionic compounds have high boiling point, because in an ionic compound, the force of attraction working between two ions is very strong and hence the bonds present are very strong, and a lot of energy is needed to break them
Answer:
The energy of a vibrating molecule is quantized much like the energy of an electron in the hydrogen atom. The energy levels of a vibrating molecule are given by the equation: En=(n+21)hv where n is a quantum number with possible values of 1, 2, ... and v is the frequency of vibration.
Explanation:
hope it helps.
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